Automatic train-control apparatus



May 22, 1928. 1,670,609 P. J. CLIFFORD AUTOMATIC TRAIN CONTROL APPARATUS Original Filed Jan. s, 1923 :5 Sheets-Sheet 2 7 M w W W A W% umnu W 0 Nu 1: K3 HIE M van vn vmu T l1 lT 1 w n FL Tull n. m N u 7 .T n MN I D NNN l N HIITIOIII. n nmu ll m \QN .I HI n E I: m n E H r N E r L "I Fills r LMwwHL MQN wiimwl .HHL F- l I 1 I l1 m3 w? N M N May '22, 1928. 1,670,609

P. J. CLIFFORD 7 AUTOMATIC TRAIN CONTROL APPARATUS Original Filed Jan. 5, 1923 5 Sheets-$heet 3 HSL CLOSEJ asww E Mam.

#1 I #3 #5 #0 O O CLEAR ADVANCE SIG/VAL CAUTION OCCUPIED Inventor! Pairick J Clgffoifi,

Patented May 22, 1928.

PATRICK J; onirroltn', or rernsrnimsynvanm, assmnon. TO THE cmrronn AUTO- MATIG TRAIN sror coMr vY, or'scnanron, PENNSYLVANIA, A CORPORATION 01? DELAWARE.

AuroinAcrIc rnarngoonrrton Aryan-Arne Application filed J'aniiar'y 5, 1923, Serial No. 610,879. Renewed August 17,1927. I

The invention in part concerns means whereby the operations ofan automatic train control system of the general character herein disclosed can be carried out without intertion of the apparatus on the vehicle. and is itself controlled by the electrical conditions in the trackway rail or rails traversed by the vehicle; This primary relayderivesitsjcurrent from the trackway rail or rails in circuit with a suitable source of current in each block, and'it is in connection with an added system of this'general" characterthat the present inventicnis to cooperate'to prevent the standard block or other signalling system from being interfered with and. giving fals indications. i

The Invention includes, however, other features, as will be hereinafter ClESCIlbG'd, and

particularly pointed out in the claimsywhich 'can be used with or wlthout association with a block signalling system.

In the accompanying drawingsz. Figure 1 1s a diagramof a slngle track road with a vehicle thereon and withthe prin'iary relay Connected up on one sidelof the vehicle or tram m'embers, such as theen gine and tender. This View shows features v battery NP; from thernega'tive side of which of th'e invention without connection or association with the" signalling' system.

Fig. 2 is a diagram of thevehicle on the rails ofa single track road with the primary relay connected up to be cont-rolled by the electrical condition in one of the rails, and

illustrating the system but showing only the track battery and av track relay representative of the signalling system. I 1

Fig: 3 is a diagram showing the means whereby interference with the signalling sys- I turn is prevented; i

Fig. 4 is a diagram of complete form. v v

Fig. fi-i's'a' diagrammatic viewof the apparatus on the vehicle.

governed means for controlling c'iertain cir- I. I g the circuitctrom battery NP throughfl 13; 1,

as, i, 8,- and back to 1 ,t1nsf nthuse-u- "solut'ely operative SOfaT screaming the in Fig. 5 shows an example of a speed Fig; 6' is diagram of the'blocksfoi the railway;

the system in more modified-forms of primary relay connections,

to be controlled by the 'drfop in potentialbetween points on the track-"system, for in turn controlling apparatuson the vehicle:

Fig. 9 isa View, diagrammatically, of .an-

which, like Fig. 1', however, cause the relay other for-mot primary relay affected by the e drop in potential butadapted-to be unafleet- ,ed by shocks or jars.

Fig. 10 shows detail.

the primary relay 'more I In Figs. liandfl the numerals, and 2; are

the trackway rails of mingle; roajd,th'e division between t-he'blocks] being indicated by the cross lines. i The primary relay PR- is; conne ted i with axles of the vehicle on one side thereof or ofthe engine and tender, it being u-nde1i.

stood that the; axles represented-may ,be I

either those of the locomotive, orone may be of the locomotive an'done of theitender'.

The direction of trafiic is in'the directionof .fthear'row- The primary relay is of a sensiti'vecharacter connected up" in a-wire oflow resistance so that the drop in=-potentialbe tween :the points'5-and6 will-be measured by the relay which in doing so will be operated so as to control the functionsof the apparatus on the ;vehicle 1 whether this be a'wire 7 extends *tothe rail 1 at point 3,

the return wire -8'leading ba cktothe post t iv'e side thebattery from point 4- on-"the J This single wire system will operate entirelyj satisfactorily on a road--not equipped with a signalling'systemybut when associated "with a signalling system: means are sometimes found necessary to be providedafor preventf mg interference with the operation-'oflthe said signal system. i

underwhicli interference with the working ofthe s'ign'al system will take place;

In this diagram,- Fig; 2,-consideri1ig. only dication through the galvanometer PR is concerned. l/Vhen, however, the signal system is considered, interference with the latter is found to exist. v

Between 3 and there is a certain drop of potentialthis drop is identical through all possible paths. In addition to the direct path, there is a path from 3, through relay T, of the signal system, through rail 2, across the car axle to 5. The division of the current through these two paths is determined by their relative resistances. In long blocks these relative values may be such that a sufficient, current-will flow through signal relay T and energize it. thus causing a false clear indlcation on the slgnals.

yIf. however, the drop of potential between tlierails can be eliminated, no current will "unduly flow through signal relay T. This is the purpose of the wiring in Fig. 3.

"By impressing equal voltages on each of the rails, 1 and 2, with current; flowing in the same direction through both of them, there 1S a negligibledifference{of potential between pointsB and9, hence no current is flowing here and signal relay remains deenergized when shunted by the iJI2L1I1-'-hn(38 ,the'signal system is unaffected and entirely normalin-its' operation, and hencea false proceed or clear indication will be prevented. This balancing system of Fig. 3 includes thewire sections 11 and 12, connected respectively tothe rail 2 at 9 and 10 at the ends of theb'lock, like the wires 7'and 8, and having therein the battery N1 the negative side'being" connected with wire ll and the positive sidewith wire 12. The rest of the system is as shown'diagrammatically in Fig.

' 2, wherein, like in Fig. l, the wires 7 and 8 are connected at, the ends of the bloclrto the rail,

In'the case with the train in the position indicated in Fig. 3, drop'of voltage from 3 to 5 in rail 1 and from point 13 to 9 of rail 2 is substantially the same.

= 'With this systemthe currentthrou'gh the relay PR-isnot affected by the length of the iwillbe understood that the elements shown train or by the presence ofanother train in the same block. The-imposed current does not interfere in any way with the roadside signals, and the indications of the primary relay yo r galvanometer PR are rendered steady, accurate,and reliable.

' Referringto 4, which shows a de velopment of the system aboveoutlin'ed, it

in light dotted lines are parts of the ordinary roadside signalling system.. e .The present'system is capable of use the automatic trainstop apparatus dis .Serial No. 553,429, of P. J. Clifford. In" that application the method, of securing the with closed in anapplication for Letters Patent ofthe' United States,.filed April 17, 1922,

indication, like the method above outlined,

purposes of the present invention.

consists in using a sensitive galvanometer I to measure the voltage drop between points on the trackway. I This indication may be obta1ned, however,

in a varietyof ways, viz: (1) The ga lvanom-' eter may be placed in a connection so as to I be affected by thedrop diagonally across the locomotive or locomotive and tender, and

.thismay be referredto as the. double rail circuit because the circuit is from one rail through the wheel on one sidediagonally to thewheel on the other rail and in this diagonal connection the galvanometer is located; (2) the measurement of the drop .in voltage may be along one side of the locomotive or vehicle or 'locomotive' and tender, as in Fig. 1 above referred to, and this requires the tsingle rail circuit; or the measurement of the drop may beinrespect tov both sides ofthe said locomotive in parallel, and this system may-be referred to as the double single rail circuit. "Figs; 3 and 4: show the circuit for uni-directional"traflic.

An essential feature of' the vplan illus-v trated in Figs. 3 and 4:. is the. impression of two equal and independent electrical'potem" tials upon twotrackway rails; in one direction to secure a proceed indication or condition; in "the other direction to secure a caution indication. The absence of this p0- tentialproduces the stopindi'catio'n or condition of the apparatus. Becausethe potentials above referred to are equal and independent, the system -will not interfere with the track circuits and no special protective devices'will-abe required'to make the Sig.

with the presentsystem particularly are those markedT and B with proper exponents indicating the respective blocks, see Fig. 4. Those marked T T T, T and T arethe ordinary track relays, such as are employed in existing signalling systems, there being combined therewith, however, additional contacts ,for, carrying out the Those marked B to B are high resistance relays for-changing the polarity of the circuits in order to secure an advance signal indication.

Two independentbatteries areinstalled in each blocln'in addition to the ordinary track batteries, in order to impress independent marked in Roman numerals I, I" to V, V,

as shown in Fig. 4. The complete independence of the sources of the two imposed currents such, as an example, as the batteries I, I, and the circuits in which they are 'lo cated is desirable in order to prevent a shunt of the track circuit, and therefore two independent line wires are employed in the system, for instance, asa't 101, 121, this being. true of each block,- and under certain conditions a third wire is used for the control of the relay B etc, in each block, this wire being marked 153 in the block being considered, though this connection may be altered.

Considering the normal operation of the circuits with the train moving through block #3, in the arrow direction 4, no other trainbeing presentzThe track relav T energized in the ordinary manner from the track battery T13 will be shunted by the presence of the train denoted by X, and its contacts will. drop, including those contacts added by the present invention. The imposed circuits, therefore, will be closed and may be traced as follow: Starting from battery IV the current flows'througrh front contact on relay B to wire 307, front contact of't'rack' relay T which remains energized (because no train is present in block #4 to shunt it), wires 30 6, 305, trackway rail 304, wire 303', back contact ol track relay T wires 302, 301, front contact of relay B and back to battery IV. The passage of the current through rail 304 contributes one-half of the condition necessary to the proceed indication, or condition on the vehicle, by the operation of the sensitive galvanomcter which responds to the drop in potential along: the tr'a'c'kway rail as above described, inconnection with the diagrams 1 to From the second added. battery I a cir cuit will be establishedthrough front contact of relay B", wire 327, front contact of track relay T wire 325, trackway rail 324, wires 323', back contact of track relay T wire 321, front contact of relay B, back to battery IV. The passage of current through rail 324 contributes the other half of the condition necessary to the proceed indication or condition on the vehicle.

It is to be understood that this condition of each rails supplying one-half of the necessary indication is true only when the locomotive is supplied with two parallel galvanometer circuits, each connected along its own side of the locomotive. In the event that the locomotive is equipped with one gab vanomet'er, the energy in" one rail- Will' be su f lici'ent to give the necessary indication. In this latter case the other rail circuit is used for the protection of the existing sign-a leystcm by balancing the electric otential atthe two sides of the track signal relays.

it will be seen that both imposed circuits are normally open until'a train enters the block, being-made by the back contacts on the track relay for that block. Hence at this time all other imposed circuits in the other blocks are normally open and no.0urrent is flowing. Certain of the relays B B etc., are energized, however, a small current flowing through theirhigh resistance windings- Considering, for instance, the relay E the current would go by the path from battery, front or back contact of the precedingor advance relay B" in this case, wires 301-352 853-306, front contacts on preceding or ad vance track relay T wires 307, front or back contact on preceding relay B and back to battery.

Stop indicatz'0n.-Thi's indication is" obtained in the block #2 behind the train by definitely.opening the imposed circuits of said block by means of the break at front contacts ontrack relay T and-this condition is illustrated in Fig. 4, wherethe contacts oi '1 have dropped consequent upon the presence of the train in block #3. Under this condition there will be no current in rails 224, 204 of this block #2, the circuits of both batteries III, III being open, and hence there will be no potential drop that can be measured by, or that will affect, the sensitive prin'iary relay or galvanomcter PR of a train coming:- intoblo'ck #2.

Hence no matter if train: enters block #2 and causes contacts of relay T to drop the imposing circuits; of rails 204, 224 will remain open and a stop indication or condition to this following train in block will result.

By the same means, i. e., the dropping of contacts of track relay T consequent upon the presence of a vehicle in block #3, the en ergizing circuit of relay B of the following block #2 will remain open, causing its contacts to drop and thus changing the polarity of the circuits in block #1, so that a vehicle, entering that block and causing the contacts of its track relay T to drop and thus making the imposed circuits through its back contacts from batteries 11 and H through rails 124 and 104', notwithstanding these actions, will receive an advance caution indication, or bring about a caution condition of the apparatus on the vehicle.

It is to be understood in this connection that the sensitivegalvanometer PR on the hence picked up, causing the block in rear of block #1 to be in. readiness to give a normal proceed indication or condition of the apparatus on the vehicle.

Now considering the conditions ensuing when the front wheels of the vehicle have entered block #4:; track relay T is now shunted and its contacts drop, closing the circuits for imposing current on the rails of block #4, and supplying the necessary proceed indication or condition to the loco1noti've as it enters this block. At the same time the imposed circuits of block #3 are opened through the front contacts of relay T. Relay T is still shunted by the back wheels of the vehicle or train, so that blocks #2 and #1 remain unchanged. Hence at this time block #1 still indicates advance caution and block #2 indicates stop, block #3 indicates stop, and block #4 indicates proceed. If the train now passes entirely into, block #4 the relative condition of blocks still. obtains, but in respect to one block in advance of those which we have been considering above. Relay T is no longer shunted and has picked up and hence block #1 now indicates proceed, block #2 caution, block #3 stop,,and block #4: proceed.

Ill)

Where in the claims the term train control apparatus is referred to, this is to be construed in a generic sense to mean that automatic train stop apparatus on the train will be controlled by the present invention, or that suitable signals on the vehicle will be operated to indicate to the engineer that he is to take action or not, as the case may be, in manually exerting control of the running of the train, or both train stop and signals may beused.

While two batteries, as for instance I, I, etc.,,have been shown herein for impressing electrical potential on the trackway rails, as above described, for controlling the primary relay on the locomotive, it will be understood that this electrical potential may be secured from sources other than these two batteries, which are shown herein as additions to each block.

For instance, the function of one of these batteries may be performed by av battery which will perform a function in connection with the signalling system and take the place of the battery used ordinarily for that purpose, as the signal operating battery.

The track relays T T etc, may be the ordinary 2 ohm or 4: ohm relays of the usual signal system. a

It will be observed that the invention is shown in connection with an end fed signalling system in which the track batteries TB, TB etc., are connected with the ends of the blocks, but theinvention is not limited in this respect.

The present apparatus, like that of the application referred to, is of the continuous control type, using a method ofconduction as the principle of its operation. It has nothing extending out or suspended downward from the vehicle, thereby eliminating the use of ramps, sliding shoes, and track magnets for induction purposes.

Continuous control is obtained whereby the engineer does not depend upon indications received at fixed wayside signal locations, but is immediately advised of the condition, or a change therein, two blocks ahead of his train. If he fails to act according to the automatic indication received, the device automatically operates to protect the train by stopping it. I

The device is electro-pneuniiatic and is operated by two electric and one air circuit, namely:

The track circuit.

The locomotive circuit.

The air circuit.

The electric track circuit is the means by which current is provided whereby the sensitive relay PR of the locomotive apparatus is energized on a clear block.

The electric circuit on the locomotive is the means by which a system of continuous signal indications are provided; this circuit also keeps an eleetro-magnet energized to hold the air brake in normal or off position. All circuits are designed to operate without interfering with the manual operation of any existing air-brake system.

All circuits are designed on the closed circuit principle; any defect in the circuits will result in an automatic brake application.

This train control unites the signal system and the air brake, making one perfect unit of both, and does not interfere with the proper operation of either one, but is so synchronized that it immediately reflects in the braking system any change in track conditions, such as an open switch, an open drawbridge, a. broken rail, or a dangerous fouling point condition that would cause asideswipe or a backing up movement against the current of traffic.

The attached drawings are for the purpose of illustrating the pinciples of operation in a clear block, an advanced signal block, a caution block, and an occupied. block.

In Fig. 5 all contacts are'shown in the position they would assume on a clear block. The polarized relay PR is shown in a connection extending diagonally of the vehicle, or in the particular illustration herein included, between the front journal box of the locomotive and the rear journal box of the tender, though this connection may extend as in Fig. 1 on one side of the vehicle, or as in Figs/i to 9. Besides the primary relay PR there are relays similar to those ofthe said Clifford application, as follows: A slow acting relay SAR, a signal relay s, and a time limit relay TL, and in addition there is used a light AYS serving the ad'- vance yellow signal, a relay Alt controlling an advai'i'ce red signal ARE), and a relay GOV. The contacts of the polarized primary relay are shown at 15, 1G and them" mature at 1T. I

\Vhen the vehicle isin a. clear bloek, the direction of current How in the polarized relay PR is such that armature 17 will make ct'int'act at 16. The path of the current will then be "from negative side of the seven battery 5B,- armature 17, contact 16, "coil of slow acting relay EAR, and to positive side of the battery.

Fig. 6 is a diagram showing where the changes in signal indications take place. While the train is in the clear block the green light '(i Fig. 5, will be displayed. As soon as the front wheels pass the insulated joints into the advance signal block #1, the engineer will receive yellow signal AYE) advising him that he is approaching a caution indication. The green light will re main displayed and advises him of the condition of the signal just passed, thus providing an absolute check upon the condition of the signalling system;

If the engineer has governed his train according to the advance caution indication received, and has brought his train down within control speed, he may pass the Cantion board. As soon as he passes the insulated joints at beginning of the caution block "#2, both lights, advance yellow AYS and clear (green G), will disa pear and a yellow Y and an advance red light ABS will take their place, advising him that he has entered a caution block, and thus checking the caution signal 'Y and advising him also of tl e condition ahead, it being assumed, oi course, that'block #3 is occupied.

ii? the train proceeds under control and for any reason the engineer becomes inca pacitate'd, an automatic application of the. brakes will be had at proper braking distance from the home block. It may be noted here that the signals clear greensignal the yellow' caution signal Y, and the reddanger signal R correspond to the wayside signals, if these are used. I

On a caution block the action of the locov motive apparatus'will differ in regard to the speed at which the train is travelling at the moment it passes the caution'b'oard. There are three different limits oi train speed which govern the automatic brake applic'a tion, namely high speed, medium speed, and low speed. These will be referred to here inafter.

Clear block any speed.

Control circuitpfhrom track rail system circuitat 23 so that relay through polarized relay PR, thus closing contacts 17, 16. This establishes circuit hem plus of battery VB to SAReontact 16, armature l"? oi PR to minus oi battery VB.

Energizing oif relay 'SAR closes circuit at 18 of a governor relay GGV, and thisis then energized and closes a circuit at 19, which energizes the signal relay S and the time limit relay TL.

The signal relay S sets arm 20 "on contact 21 and the green (clear) signal G is lighted, the circuit thereth'rough being hem plus to minus ofthebattery. I

The energizing-of time limit relay TL keeps its armature at 23 closed and hence solenoid will be maintained energized, and as lthis'is the solenoid which controls the EAV valv'e or trigger valve of the Glitford application, the brakes will be held off. An advance red signal relay AR will also be energized, but this will have no client in lighting the advance red signal ARE: because of the circuit being open at 22.

In the above example all of the relays on the vehicle are energized and their contacts are picked up. The governor contacts LSL and HSL are open. LSL closes' below low speed limit and ESL closes below high speed limit. v p

Adoan'ce signal M002 0.

Now supposing the vehicle enters block' #1, Figs. i and 6, which is the second block on the approach side away'i'rom the occu p'ie'd block #3, and in which block #1, as above deseribed, the polarity of the imposed current has been changed for the purpose or getting an advance caution indication, the

result will be that the armature 17 of polariz'ed relay PR, because of the change of polarity of the circuit 'derit'ed from the trackage, will contact with poi-n t 15 instead or point 16, and hence the circuit will be closed through the advance yell'ow signal AYS to warn the engineer that hei's approaching a caution board, having no effect, however, upon the automatic braking system, because solenoid 30 remains energized.

Under these, conditions coil AY will be energized,closing-contact at 28 andmaintai-ning energizedthe slowacting relay SAR, which because of its slow action does not become de-energized while armature 17 of PR is pa-ssing from ld'toloand hence does not open circuit at 18[ This maintains con:

tacts at 18 closed and maintains energized the relay GOV, which maintains the circuits at 19, 24, thus mainta-ining th'e relays S TL energized, the latter maintaining the AR and solenoid 30 will remain energized. The result of maintaining the relay S energized that the green clear signal G will be main tained by making contact at 20, 21 and this 1 green signal will exist simultaneously with the advance yellow signal AYS. This will enable the engineer to check up on the operativeness of the roadside signals, and will give him an indication of the condition of the signal being approached, which may be around a curve or in like situation where he yet can not observe it. The automatic stop mechanism will not be operated in the above example because the solenoid 30 will be maintained energized.

The maintaining energized of the relay AR will maintain contact arm 25 on point 26, but the circuit to this contact and therefore to lamp AR advance red will be broken at 20, 22, hence only the green and ad- Vance yellow signals will be displayed.

Signals AYS and ABS indicate'the conditions of the signals in advance or those being approached, and Y and G indicate the conditions of the signals last passed. Signal R indicates that a brake application has been efiected, as foretold by the signal ARS.

Dead block at high speed.

Now if the vehicle runs into a caution or dead block as #2, i. e., one in which there is no current'in the trackway, and calling for a stop, the relay PR will be dc-energized and its contact arm 17 will assume neutral position between contacts 15 and 16. Relay SAR will be dc-energized, opening circuit at 18, thus de-energizing relay GOV, which will open circuit at 19, de-energizing signal relay S, and causing arm 20 to contact with point 22. De-energizing of the relay GOV will also break the circuit at 2%, HSL be ing open thus de-energizing relay AR and allowing arm 25 to break contact with point 26 and make it at 27, with the result that the red light R will be displayed.

The automatic train stop circuit will be broken at 24 by the de-energizing of the relay GOV and the solenoid coil 30 will be deenergized, and hence, as set forth in the Clifford application, the brakes will be applied for a stop.

Passing a caution or distant indication (a board at 45 for day and a yellow light for night), or in other words, passing from block #1 into block #2 of Fig. 4 at moderate control speed.

Now if the engineer has acted according to the indication given by the advance caustion signal AYS, while in block #1, and has slowed down his train, simultaneously, on passing the insulated joints of the distance signal or caution board, the green G and AYS (advance yellow) lights will go out and the yellow light Y and ABS (advance red signal) will take their places. This will be due to the following conditions which will be set up: I

. All relays except relay AR will be de-energized. LSL (low speed limit) contact of the speed governor SG will be open and HSL (high speed limit) contact will be closed. Relay AR and solenoid 30 will stay energized for a predetermined time, or until the armature of time limit relay TL, at 23, has travelled a certain distance necessary before opening the circuit. During this predet-ermined time the path of current flow will be from plus of battery VB through relay AR and through solenoid 30, contact 23 of TL relay, which has not opened yet, and point 29. The current is diverted here to closed contacts at HSL by reason of circuit at 24% being open, through speed governor common wire CW to point 31 to minus of battery.

The result of this condition will be that circuit will be closed at 25, 26, contact will be closed at 20, 22 of signal relay S, and cur.- rent will go from plus of battery through both ARS (advance red signal) and through yellow light Y to minus of battery. This combination of signals will persist until the TL relay breaks the circuit at 23.

The said combination of signals will tell the engineer while in block #2 that he has passed a distance indication (caution board) because he sees the light Y, and observing of the light ABS, indicates to him that he is approaching a home board or stop indication. He will also get a stop it the train runs beyond the time interval necessary to open the circuit at 23 by the time limit relay. This interval will allow the train to traverse, say V of the caution block, well within braking distance from the home boar-d. It the train passes over the "7 distance, then the automatic brake apparatus will operate to stop the train, because the relay TL will break the circuit at 23 and the solenoid 30 will be de-energized. This will de-energize relay AR and arm 25 will then break the circuit at 26, putting outlights Y and ABS, and make the circuit at 27 and lighting the danger signal R.

A train running at anv arbitrary low speed.

If an engineer on approaching a home board reduces his speed down to an arbitrarily prescribed low limit, say, of 4 miles an hour, he can pass the home board into the occupied block, in order, for instance, to assist another train which may be stalled for lack of power, or to search for the reason that caused the Wayside signal to display a stop indication.

It will be obvious that this eliminates automatic braking and he can proceed as long as this prescribed slow speed is maintained, or until the condition or obstruction is re moved.

The conditions obtaining under slow speed when the engineer is approaching the occupied block are as follows: The contact arm 17 of relay PR will be in neutral posigoes through the advance signal light ABS and through the yellow signal Y to minus or battery. As the speed overned low speed limit contact 'LSL is closed, the current through the solenoid 3Q will be from plusotbattery to point 32, through the solenoid to point 30, through LSL, and common wire ClV of governor to point 31, and thence to minus of battery, and the brakes will be held off. Breaking of time'limit contact at 23 I will not affect this circuit.

Should the engineer attempt to accelerate his speed, "the contact'LSL of the speed governed means SG will open, thus opening the circuit through the solenoid, causing the brakes-to be applied automatically, and the train will be stopped, it being understood that the circuit at 24: is already open, due to deenergized relay SAR.

The sensitive relay PR is designed to Withstand shock, oscillation and jar. and

closes on its contacts at approximately 1.5 millivolts. Thetrack wiring is designed to give, say ten times more voltage than is required for operation.

It will be-understood from the above that going at 1'5 miles an hour, which is arbitrarily fixed as a control speed, if the engineer passes a distant or caution signal into a dead block, he can proceed until the time limit rel ayopens thecircuit at 23, after the lapse of-the prescribed time, whereupon he will get a red signal and an automatic stop, if he has not already taken action, or if the conditions ahead have remained unchanged. If the conditions ahead clear, then he can proceed, the automatic system having no eflect.

Referring to the modified forms of primary relay connections, Fig. 7 shows the relay connected in parallel with both rails. If the connection on one side should go out oi": service that on the other side will still operate the relay. 1

In Fig. 8 the drop in potential which is utilized to operate the primary relay is that taking place between the front wheel and axle on one side and the rear wheel and axle on the other side of the vehicle or engine and tender combined.

In Fig. 9 is shown a modified form of relay which will be substantially unaliected by shocks or jars. It includes two swinging arms a, 7) and associated coils for controlling them, each being in its own connection receiving current because of-the drop in potential between its points-of contact with the axles, wheels and 'trac kage, and each arm has back and front contacts e, d, the two front contacts ebeing electrically connected, and the two back contacts d are also electrically connected, the result being 'thatt-he pair of contacts for-one arm is displaced 180 in respect to the other pair of contacts d and e of the left hand pair being respec' tively at left and right of their armature, while (Z and e of the other pair being at right and left respectively of their armature. Under one condition of the trackage, electrically consideredyboth arms Will be on their front contacts, and under an absence of this condition they will swing toneutral position, whereas upon change of polarity of the track current both arms will be on their back contacts d. 'lVhen in the position shown,or if both are on their contactsxd, it willbe seen that shock or jar which will tend to dislodge one arm from its contact will tend to press the other arm harder '11P", on its contact, and hence the circuit controlled by this relay will'bemaintainetL-and this is true under a reversed polarity of the trackage circuit. Another advantage of this relay is that if one connection is broken the other will maintain the desired circuit.

Like in the said application of Clifford, the primary relay is mounted on an engine or engine and tender of any standard type. It is operated by the current in its conductor connected with points on the track system between which a drop in potential *takes place. Similarly no insulating of axles,

wheels, or other parts of the standard ve-' h'icle equipment is necessary, and the tracks of the railwayare o-fthe standard type, hav ing no spe'cialsections, and giving continuous control. The conducting wire in which the relay is located may be connected with the axle journal boxes whereby the current will be received 'thl'Ougll the brassesthereof, as stated in an application of even date herewith, though the invention is not limited in this respect. 1

Where the system is used in connection with a wayside signalling system the primary relay, may be such as to beunafi'ected by the signalling current alone, its operation one way depending upon the current imposed on the trackage additionally to that used for wayside signalling, and its operation to neutral being due to absence of the imposed current and its reversal to achange of polarity of the imposedcurrent.

The primary relay 'PR-is of the Depre" DArsonval type, its armatures or pointers closing on its contacts on, say, potential above plus or minus 1.5 anillivolt. This type or" relay is like that made' byfl he Weston Electrical InstrumentCompany of Newark, N. 5., model 30. anddisclosed as to its general features in Letters Patent of the a bridge between the terminals of the coil or spool and the current produced by the tendency or the spool to vibrate, when receiving no current from the rail, and when subjected to jar a shock will oppose the vibration of the coil and thus maintain the pointer or swinging arm in neutral position out of engagement with its contacts, thus rendering the relay suitable for controlling apparatus on a locomotive where more or less vibration necessarily takes place.

In the drawlngthe spool is shown as connected directly with its leads, the coil springs ordinarily used between the spool terminals andv the leads being on'iitted for clearness of illustration.

The current imposed on the track may be say 7 amperes.

The speed governed means SG may be of the general form disclosed in said prior application, wherein a centrifuge operates a contact ow to close contacts HSL and LSL, Fig. 5.

The time limit relay like in said application may have its armature retarded and slidable along a long contact, indicated diagrammatically at 23, Fig.5.

The resultof deenergizing the solenoid 30 is that train line air will be released for setting the brakes.

Features relating to the primary relay per se and its connection with the track system are claimed in an application filed of even date herewith, Serial Number 610,880, and in application No. 620,286, filed February 20, 1923. Other features are claimed in the application Serial Number 553,429 of June 17, 1922.

I claim 1. In combination in train control apparatus a non-inductive primary relay on the vehicle to control the operation of apparatus 'thereon, said .relay being electrically connected conductively with the track system to be aliected by the drop in potential between its points or contact with said track system, a roadside signalling system including a track way relay for each block for controlling the operation of the signals, means for energizing the tracks by direct current for signalling, and for imposing additional direct electric potential upon said track system, when the block is occupied and for Withholding said imposed current from the block in rear of the occupied block, for op erating the said primary relay and means for preventing said imposed direct electr c potential from interfering with the operation of the signal system, substantially as described.

2. In combination in train control apparatus a primary relay on the vehicle to control the operation of apparatus thereon, said relay being electrically connected conductively with the track system to be affected by the drop in potential between its points of contact with said track system, a roadside signalling system including a track Way relay for each block for controlling the oper-- ation of the signals, means for energizing the tracks for signalling, and for imposing additional electric potential upon said track system, when the block is occupied, for operating the said primary relay and means for preventing said imposed electric potential from interfering with the operation of the signal system, said means consisting of a source of current and a circuit for imposmg electric potential, to balance the 1m-.

li U

trackway rails atseparated points to be operated by the drop in potential between said points, a roadside signalling apparatusineluding in each block a track relay for controlling the signals, means tor energizing the rails for signalling, and for imposing additional electrical potential on the rail with which the primary relay is connected, when the block is occupied, and means for impressing upon the other rail, at the same time, electrical potential substantially equal to that imposed on the rail first mentioned to prevent interference with the operation of the trackway relay and the signals belonging to said block. I

4. In combination in train control apparatus, a direct current primary relay on the vehicle to control the operation of apparatus thereon, said primary relay being arranged conductively to measure the drop in electrical potential between separated points along the tracks, track relays for controlling the operation of the signals, means at each block for impressing additional direct electrical potential upon the blocks for operating the said primary relay upon the entrance of the Vehicle into the blocks, and means whereby the direct electrical potential will be balanced on the two sides of said track relay to rails with direct current and for imposing additional direct electric potential upon the rail with which the primary relay is .connected for controlling the same, and means ctor simultaneously imposing upon the other rail a direct current of potential substantially equal to the additional potential first mentioned so to balance the imposed potentials at both sides-of the track relay'so that the normal operation of thesaid relay will not be interfered with, both the imposed. and the balancing circuits being connected at the ends of-the trackway rail system ofthe block,substantially as described.

6. In combination in train control apparatus. a direct current primary relayion the vehicle electrically and couductiyely con-' nected to separated points on one otthe rails to control the operation of apparatus thereon, a road side signalling;apparatus including a track relay for'each block for controlin; the operation of the signals, said relay being connected across the trackway rails, means at each block for energizing the rails with direct currrmtand for imposing. additional direct electric potential upon the rail with which the primary relay is connected for controllin'g'the same, and means for simultaneouslyimposing upon the other rail a current of potential substantially equal .to the additional potential first mentioned so as loibalance the imposed potential at both sides of the track relay so that he normal operation otthe said relay will not be interfered with, said imposed circuits connecting With the ends of the rails'of the blocks. the acditional electric currents imposed upon the two rails being derived from independent sources. I

,7. In combination in train control apparatus. a primary relay on the Vehicle sensitiveto variations in :the electrical condition otthe track rails of the block, a relay in each block for controlling the signals along the roadside, a circuit for each rail of the track in each block, contacts controlled by the track relays for closing said circuits When the relay oi the block belonging thereto is shunted by the presence of the train, said circuits being also closed at the-frontcontacts of the relay of the unoccupied block next ahead,.an.d means for imposing current scribed,

uponsaidcircuits When closed and upon the said .prin'iary relay, the corresponding circuit of thenext' following block .remainingopen so long-as the block ahead remains occupied audits relay deenergized to thereby operate the signals.

a rin'iary relay on the vehicle to control the apparatus on said vehicle, and deriving its to In combination in'a train control system current conductivelyv from the track system, i

a roadside signallingapparatus witha track relay; in each block, means for energizingithe rails of the block with which said relay lS connected, and circuit connections 'for ,impressing additional current for controlling the primary relay, said circuit connections being closedby the dropping oit track relay contacts of the occupied block, consequent upon. the presence ota vehicle in. the block and the shunting of the track relay belonging thereto, said circuit connection being closed by the front contacts of theenergized track relay ofthe unoccupied block ahead, the corresponding circuit connections or" the block next following the occupied blockbeing open so long as the condition of the occupiedblock is maintained, whereby a ve hicle entering said next following block will receive no additionally imposed current through its primary relay, substantially as described. I

9. In combination in a train control "sys- .tem prin'iary relay onthe-vehicle to control apparatus on the said vehicle, said primary relaybeing electricallyand conductiyely 'connected with the track system, a signal con trolling relay in each block having in additionto its signal contactsothercontacts controlling circuit connections. to the track system, for imposing current thereupon for controlling, the operation ofthe primary relay on the .vehicle, said circuit connections I being; controlled also by the signalling relay of the next block ahead in the current of trafiic pandeaeli of said relays being deenergized by the presence of a Vehicle :in its block, .to close said circuit connections, a pole changing relay in each' block, the eincult of which iscontrolledjby the signalling relay ott-said next block ahead, due to 'the presence or absence of a vehicle thereirnand each lot-said polechanging relays controlling the polarity of the circuit of the next block in its rear, inthe current oftraffiqsaidpri inary relay being polarized so that the reversal of the polarity ofits'controllingcircuitdue to the deenerg'izing of the pole changing relay of the stop block will cause said polarized primary relay to indicatcan advance caution signal,substantially, as de- 10'. Iii-combination in train control. apparatus, a priinarypolarized relay on the vehicle toricontrolling apparatus thereon, said relay being in electricaland conductive connection with the'track system, means for 1mposing current upon the trackage of a block as a consequence of the vehicle entering said block to control the prin'iary relay, for a proceed ind- :ation, or condition of the ap, paratus on. the vehicle and for simultaneously" opening the circuit of the next following block in the direction of the trafiic to control the primary relay of the vehicle of that block for producing a prescribed indication or condition, and means for reversing the polarity of the circuit in the block in rear of the cantion block for operating the primary relay of the vehicle entering" said block to produce an advance caution indication, substantially as described.

11." In combination in train control apparatus, a primary polarized relay on the vehicle forcontroiling apparatus thereon. said relay being" in electrical and conductive connection with the track system, means for im posing current upon the track system of a block as a consequence of the vehicle entering said block to control the primary relay, for a proceed indication or condition of the apparatus on the vehicle and for simultaneously opening: the circuit of the next following block in the directionof the traffic to control the primary relay of the vehicle of that block for producing a prescribed indication or condition, speed controlled means for determining Whether said indication or condition will be for caution or stop, and means tor reversing the polarity of the circuit in the block in rear of the cantion block for operating the primary relay of the vehicleentering said block to produce an advance caution indication, substantially as described.

12. In combination in train control apparatus, a 'prin'iary polarized relay controlled as to its position by the presence, absence. or reversal of the current of the block, signal means onthe vehicle having an indication.

for advance caution, caution, clear and danger conditions, to distinguish each condition from the others, means for energizing ablock as a consequence of its occupancy under proceed conditions, and for simultaneously deenergizing the caution block and energizing the advance caution block in the reverse direction, said polarized relay controlling the said signals, the advance caution signal being displayed when the primary re lay changes under the reversal of polarity of the current from its normal direction, subdanger conditions, to distinguish each condi+ tion from the others, means for energizing a block as a consequence of its occupancy under proceed conditions, and for simultaneously deenergizin'g the caution block and energizing the advance caution block in the reverse direction, said polarized relay controlling the said signals, the advance cant-ion signal being displayed when the primary relay changes under the reversal of polarity of the current from its normal direction, the clear signal persisting simultaneously with the advance caution signal.

14. In combination in atrain control system, a primary polarized relay 011 the 've hicle, controlled by the presence and absence of prescribed currentin the block, and by the changes in polarity of said current, means on the vehicle controlled by said relay, and means affected by the vehicle in. an o'ccupied block, for establishing said pre scribed current in said block, for absenting said prescribed current from the adjacent caution block, and for reversing the polarity of the said prescribed current in the approach block adjacent the caution" block i. e., in the block on the opposite side of the caution block from the occupied block.

15. In combination in a train control system, a .primary polarized relay on the'vehicle, controlled by the presence and absence of prescribed current in the block, and by the changes in polarity of said current, means on the vehicle controlled bysaid primary relay, and means affected by the vehicle in an occupied block, for establishing polarity of the said prescribed current in the approach block adjacent the caution block, i. e., in the block on the opposite side of the caution block from the occupied block, and brake apparatus controlled by said primary relay to withhold a brake api said prescribed current in said block, for absenting said prescribed current from the ad acentcaution block, and for reversing the uncompeblock, and for reversiug 'the polarity i of said prescribed current in the approach block, i. e., the block on the opposite side otth'e caution block fromthe occupied blo'ck, substantially asdescribed. V

'17. "In-combination in a train control system, a primary polarized relay on the vepolarity of the said prescribed, current in the approach block adjacent the caution block, i-.e.,-in the block on theoppositeside of the caution bloc'k from the occupied block; and signals'on the vehicle for indicating the condition'oli the blocks, substantially as described. I

18. In "combination in a train control systemya primary relay on thevehicle in a conductor having its-terminals in continuous contact with the traffic rail system and receiving curr'entconductive'ly due to the drop in potential between said terminals, means affected by the vehicle for imposing direct currcntupon the rail system" of an occupied block for absenting said current t'rom the railsystem of the eau'tionblock and for re versing the polarity" of said direct current in the rails o't'vthe advance caution block, i.e., the block-on the other side ot'the caution block from the occupied block, and means on the vehicle controlled by said primary relay', substa1itia=lly as described; I 19. In I combination in a train control system, a primary polarized relay 'onthe vehicle, controlled by thepresence and absence of prescribed currcnt'in the block and by changes in polarity of said current a slow acting relay controlled by the primary relay, means on the vehicle controlled by said slow acting relay and means affected by the vehicle-fin an occupied block for imposing current of normal polarity in the rail system thereof, for, absentin'g current from the railsoii the-caution block, and-for reversing the polarity of the-current in'the advance caution block, substantially as described. 1

20. In combination in a train control system, a primary polarized relay on the vehicle, a circuit in each block to control the primary relay olthe vehicle entering said block; eachof-said circuit-s being controlled by a pair of relays one of which is in one block and the otherin 'the adjacent block, the'circuit of the occupied'block being closed by thepresence 0t the'vehic'le "therein, relays in each block for changing the polarity of the controlling circuit for the primary 'relayuo'f' t-he next "following block, in the 'd'ie rection'of trafiic, each of sai'd'latter relays being controlled by the circuit controlling relay of the block in advance in the direction ofitraliic so'that When the" controlling circuit of saidiadvance block is closed c0n'se quent upon the presenceof a vehiclet-herein, the polarity changing; relay of the next following block Willbe operated to change the-polarityof the controlling circuit of the next block in its rear to cause the primary relay ofthevehicle in said block toindicate an advance caution condition, substantially as described.

21. In combination in a train control sys- IEU.

tem a primary polarized relay on the vehicle, a circuit in each blOCk'itO controlxthe primary relay of the vehicle enteringisaid block each of said circuits being controlled by a pair of relays one Of'WlllCh is'in, one block and the other, in the adjacent block, the circuit ofthe occupied 'block'bei'ng closed by the presence of the vehicle therein, relays in each block for changing the polarity of the controlling circuit for the primary relay of the next following block, in the direction of traffic, each of said latter relays being controlled by the circuit controlling relay of the block in azdvance so that when the controllingv circuit of said advance block is v closed consequent upon the presence-of arehicle'thcrein,the polarity changing relay of i the next following block will be'operated to change the polarityjof the controll1ng3c1r-' 'cuit-of the next block inits rear to cause the primaryrelay of the vehicle insaid block'to indicatean 'advance caution signal, the close ing of the circuit in thG'OCCUpIGd block opening the. primary relay controlling circuit of the said next tollowing'block-to secure a prescribed indication or condition of the apparatus on thevehicleientermg the last mentioned block, substantially as described:

lirtrain control apparatus, aipriinary relay on the vehicle for controlling apparat'us thereon said primary relay being 1n a coi'uluctor having its terminals'in continuous electrical 'oonnection wvith themtr'ack rails and receiving; direct; current (1116,1130 the I drop in potential between thepoints of contact with the rails, atrackbattery for each bloclna relay in cachtrack battery-circuit, a circuit in each block inrespect to Whiclrthe primary relays cut in upon the entranceot a vehicle, into the-block, saidcircruts being closed'by the shuntingof thetrack 'relay o't' ratus thereon said'primaryarelay beingin a the occupied'bloc'k and the'maintained ener- .a relay in each conductor having its terminals in continuous electrical connection withthe track rails and-receiving direct current due to the drop in potential between the points of contact withthe rails, 21 track battery for each block, track battery circuit, a circuit in each block in respect to which the primary relays cut in, upon the entrance a vehicle into the block, said circuits beiug closed by the shunting oi the track relay of the occupied block, and the maintained energized condition of the track rclay in. the block. ahead in the direction of tralilc. the closing of said circuit at the shunted relay opening the circuit of the next following block, each of said relays controlling signals on the roadway, substantially as v described.

24. In train control apparatus, a primary relay on the vehicle for controlling apparatus thereon, a track battery for each block, a relayin each track battery circuit, a circuit in each block in respect to which the primary relays-cut in,upon the entrance of a vehicle into the block, said circuits being closed by the shunting of the track relay of the occupied block and the maintained energized condition of the track relay in the bldck ahead in the direction of traflic, the closing of said circuit at the shunted relay opening the circuit of the next following block, a relay in each block for changing the polarity of the controlling circuit of the next-block in its rear, each of said pole.

changing relays being controlled by the relay of the controlling circuit of theblock next ahead. substantially as described,

In combination in train control ap.- paratus, a three position polarized relay on the vehicle, means for delivering a current thereto of different polarity according to the electrical conditions in the blocks of the rail- 7 way, signals on the vehicle giving a clear, caution and danger signal according to the setting of said polarized relay when the current is of one polarity, an advance signal on the vehicle controlled by the said relay and displayed when the polarity of said current is changed, said advance signalbeing distinctive in respect to the other signal in dications substantially as described.

26. In train control apparatus, a track divided into blocks with means for reversing the polarity of a circuit in a block when,

the second block ahead is obstructed, a polari zed relay on the vehicle receiving current from the said circuit, an advance signal on the vehicle to give an indication of the condition ahead. signals on the vehicle corresponding to block signalsgwvhether the latter are used or not, said advance signal being displayed as a consequence of the polarized relay receiving a current reversed as to polarity, substantially as described.

27. In train control apparatus, a track divided into blocks with means for reversing the polarity ofa circuitin a block WllGIltllt! second block ahead is obstructed, a polarized relay on the vehicle energizedfroin the block circuit, an advance caution signal on the vehicle to give an indication of the conditrons ahead, other signals on the vehicle tor clear, caution, and danger, all of said signals being controlled by the primary relay, said advance caution signal being displayed as a consequence of the polarized relay becoming energized and reversing its position from a reverse polarity block circuit, substantially as described. i

28. In train control apparatus, a track divided into blocks with means for reversing the polarity of a circuit in a block When the second block ahead is obstructed, a polarized .a reverse polarity block circuit, and brake applying means controlled by the primary relay to holdthe brakes off when said relay energized and to apply the brakes when said relay is deenergized.

29.,In train control' apparatus, a track divided into blocks Withmeans for reversing the polarity of a circuit in a block when the second block ahead is obstructed, a'polarized relay on the vehicle receiving energy from the said circuit, an advance signal on the vehicle to give an indication of the condition ahead, signals on'the vehicle correspond ing to block signals, whether the latter are used or not, said advance signal beingdisplayed as a consequence of the polarized re- J'Un lay receiving a current reversed as to poin a block When the second block ahead is obstructed, a primary polarized relay on the vehicle receiving energy from saidcircuit, an advance caution signal on the vehicle displayed as a consequence of the setting of-thc said polarized relay by the change in the polarity of the trackway circuit, and means controlled by said primary relay for displaying a clear signal simultaneously with the advance caution signal, and means controlled by said primary relay for main taining the brakes off while said advance signal is displayed, Y substantially as described.

31. In combination in train control appamama rattle/,1. speedgovernedmeans" on-the veh-icl'e,-- a contact controlled. thereby; to be elosed--.=a,t.. a: moderate control speed,- aw caution signal.

and .anyadvance dangerasignal on-the. ve=

hicle, saidnprimary relay being controlled by the electrical condition of; a circuit in thecau-tion. block, which operates to: set said reilay for displaying said signals simultaneousllyand when. said moderate speed governed contact is closed, substantially as; described.

82. In combination in. traincontrol appa ratns, speed governed. means on the vehicle,

a contact controlled therebyto; be closed at, a. moderate control speed, a caution signal and an advance danger signal. on thevehi'cle, saldprimary relay benig c ontrollediby the electrical condition of a circuit in the cau.-.-. tion block, which operates-toset said relay for displaying said signals simultaneously and when said moderate speed governed.

contact is closed, a time limit relay, electromagnetic means for controlling the brakes, a danger signal, the contact of the said time limit relay when open causing the electromagnetic means to set the brakes, relay means controlling the said caution, advance danger, and danger signals and in turn'controlled by the time limit relay so that when the latter opens the caution and advance danger signals Wlll go out and the danger signal will be set, substantially as described.

33. In combination, a. primary relay on the vehicle having a contact arm which is moved to neutral position by the electrical condition of a caution block, a caution and an advance danger signal on the locomotive,

a solenoid for controlling automatic brake applying means and keeping the same off when energized, speed governed means which makes a contact at a prescribed low speed, and

the solenoid, substantially as described.

34. In combination in automatic train control. means for imposing electric potential on the track system in each occupied block and for removing said electric poten tial in a caution block and for changing the polarity of said electric potential of the block on the approach side of the said cantion block, signals on the locomotive, a 'primaryrelay on the locomotive to be set in different conditions by the electrical condition of the track system of the blocks, an

advance caution signal on the vehicle diselectrical means which when saidcontact is closed displays the said caution and advance danger signals and energizes many 'relay thenputting I the; advance" caution and: the: ole ar signals. out, substantially asdescribed, .o

35oilnacombination in. a train control mechanism, signals. on the vehicle .correspending-to block signals, and other s1g-- nal-s,,onebeing an! advance caution signal f andthe'other an advance diangersignal, and a'primary. said signals, to -make those. correspondingto block, signals harmonize. therewith andto relay on. the vehicle 1 controlling. i

sin'niltaneously display with thenclear nbilock signal. the advance caution .si'gna-l and to display with the caution block signal'the ad's vance' danger. signal, and. todispl ay etlie danger signal alone,.,'said vehicle. signals.abeing-. ein-ployectwith. or w thout wayside signals.

ling means, substantially asdescribed.

36. In combination, ized relayon the vehicle, a slow acting relay the circuit of which is controlled by the primary relay, an auxiliary relay in circuit with one of the contacts of the polarized relay and controlling a. circuit'inaker for the slow acting relay, a governor relay, a circuit'breaker therefor controlled by the slow a signal relay and a time limit acting relay, relay, the circuit of which is controlled by the governor relay, signals, the circuits of which are controlled by the signal relay, an

athreepositio-n polarg advance signal relay controlling the circuit to certain of said signals jointly with the signal relay, an advance dangersignal also controlled, by the signal and advance signal relay, the circuit of advance "danger signal relay being controlled by the time limit relay, a speed and high speed limit contacts, acommon Inn governor having low speed limit wire for said contacts on oneside thereof,

circuit controllers, one for diverting current through the low speed limit contact and con trolled by the lame limit relay, and the other for diverting current through the high speed limit contact and controlled by the governor relay, but for the time prescribed by the time limit relay through its circuit controller, a solenoid which when energized holds the brakes ofi, said solenoid being deenergized when the polarized relay is in neutral conditionor when the time limit relay opens the circuit of the .high limit contact of the governor, and an advance caution" signal in circuit with the pole of the polar- I ized relay which is in circuit when the polarity is reversed, substantially as described.

37. In combination, in train control apparatus, an advance signal in thecab displaying the character of signal belonging to the block being approached, the cab s'ignal belonging to the block being traversed persisting with said advance signal throughout that block, means for operating said signals electrically from the electrical condition of.

the block'beingtraversed for a continuous indication, I

38. In combination in train control ap paratus, anadvance signal in the cab dis-' playing the character of signal belonging tothe block being approached, the cab signal belonging to the block being traversed persisting with saidadvance signal throughout that block, means; for operating said signals electrically from the electrical condition of theblock being traversedfor-a continuous;

advance caution, electrical apparatuson the vehicle-affected by the presence, absence, or

apparatus, signals on the vehicle for clear, caution, danger, and

polarity of electric energy in the block for controlling said signals, means for; imposing electric energy on an occupied block to cause the vehicle apparatus "to display the said clear signal, for absenting said energy in a caution block and thereby displaying said caution signal, and for reversing the polarity of the electric energy in the advance caution block and thereby displaying theadvance caution signal, and ,electro-niagnetic means on the vehicle for holding the brakes 01f unrler normal and reverse polarized condition otthe block and to cause the setting the block, substantially as described.

I brakes under absence of current from the ture.

In testimony whereof, I alibi my signa-' PATRICK J. CLIFFORD; i 

